Completion structures of the type disclosed in U.S. Pat. Nos. 5,332,045 and 5,180,016, which are incorporated herein by reference, are often used in horizontal or gravel pack well bores.
These completion structures are generally comprised of several different completion apparatuses that are coupled together and work in concert to perform various completion and testing operations within the well bore. A hydraulically actuated packer of the type disclosed in U.S. Pat. No. 4,832,129, which is incorporated herein by reference, is usually positioned at the upper portion of the bottom hole completion structure and is connected to the earth's surface via a tubular work string and setting tool that extends into the packer assembly. The packer is, in turn, connected to a completion assembly that extends downhole to the end (i.e. "bottom") of the well bore. The purpose of the packer, of course, is to isolate downhole portions of the well bore from the hydrostatic head above the packer.
Located downhole and attached to the setting tool is a tubular extension or wash pipe, a conventional shifting tool having a shifting key and cup-packers associated therewith. The cup-packers are positioned a distance uphole from the shifting tool, and the shifting key is connected to the shifting tool. When the completion structure is initially run into the well bore and positioned on the bottom for fluid circulation, the shifting tool and the cup-packers are typically positioned downhole near the bottom of the completion structure. Both the shifting tool and the cup-packers are coupled to the wash pipe to thereby move with the wash pipe as the wash pipe is pulled uphole via the work string. The cup-packers perform the conventional function of closing ports with the completion tool to change fluid flow path within a portion of the completion tool during different stages of the testing or completion operation.
The shifting tool is used to actuate other devices within the completion tool such as a slidable flapper sleeve that, when actuated, allows a flapper valve to move to a closed position and thereby change or restrict the fluid flow path within another portion of the completion tool. In addition, the shifting tool engages and closes a closing port sleeve, which is positioned between the packer and the flapper valve. The closing of the closing port sleeve also changes the fluid flow path through the completion structure.
Filter screens also form a part of the conventional completion structure. Such filtration devices typically include screens that are used to filter out sand and fines from a geological formation from which gas or oil may be produced. The screens conventionally comprise one or more wrapped wire well screens or one or more dual concentric wrapped wire well screens having an annulus between the concentric screens that have been packed with sand, gravel or epoxy-coated gravel. The screens are typically run in the uncased portion of the well bore to retard the flow of sand fines into the production tubing along with the produced fluids and are positioned across the geological formation between the flapper valve and the bottom of the well bore.
In conventional completion structures and in a manner known to those skilled in the art, the shifting tool and cup-packers simultaneously move with the wash pipe as the wash pipe is pulled uphole to achieve various fluid flow paths that are required in completion and testing operations. As these devices are pulled uphole through the well bore, the cup-packers cover fluid ports and the shifting tool actuates flapper valves and covering sleeves to change the fluid flow path in and around the completion structure as desired.
While these completion structures are quite useful in many horizontal and gravel-pack well bores, they do, by their conventional design, impose certain limitations within the completion structure. For example in conventional systems, the bores within the completion tool, including the screens, are such that the shifting tool size, the cup-packer size and the flapper size are all relatively the same. Thus, conventional shifting tools have been limited to those completion structures that have a consistent inside diameter bore throughout the length of the tool in which the various shifting operations and port closing operations occur.
This limitation presents a problem in that when for example screens having a small inside diameter relative to the packer and closing sleeve are attached to the completion structure, conventional shifting keys are not able to expand far enough to engage a sleeve shoulder in a bore having a larger inside diameter, since there may be as much as 3/8" to 1" difference in the inside diameter between the bore downhole and the bore where the flapper valve and closing sleeve are positioned.
While there are shifters that will extend from the centerline of the completion structure bore to engage a larger size inside diameter, they are limited in the amount of load that they can withstand. The reason these conventional shifters are limited is that as they extend farther, the tool strength that is available and necessary to shear a shear pin or apply force that allows other shifting operations to occur becomes less.
A problem arises in those instances where it is desirable to have a larger inside bore diameter in those portions of the completion structure in which the flapper valve and the closing sleeve are located. One such instance is where it is desired to have more fluid flow or by-pass area between the wash pipe and the packer mandrel. Greater by-pass area is desirable because in some configurations where the space between the wash pipe and the packer mandrel becomes too small, solids in the fluid can build up in those restricted areas and plug it off, thereby affecting the fluid flow in the system. In these instances, the conventional shifters are not well suited because if the inside diameter of the filter screens are 3/8" to 1" smaller than the inside bore diameter in which the flapper valve and closing sleeve are located, the shifter will fail to properly engage and shift those devices. As such, a new completion tool has to be built for each wash screen size to accommodate the smaller inside diameters of each varying size of wash screen, which, thereby, increases the costs associated with the use of the tool.
Therefore, it is seen that there is a need in the art for a shifting tool that can be used in different bore sections of a completion structure having differing inside diameters. The shifting tool of the present invention provides a shifting tool that addresses the deficiencies of the prior art.